Hydraulic pump or motor



May 26, 1942. J. ROBINSON HYDRAULIC PUMP 0R MOTOR Filed June 28, 1959 R o, om wm m E W f m sm w im, N. N .V O Q W\ I l @n Y Q www OG 06 Nb 1li m m -Mm .vm l l e@ Il l.. I \o& NN @.7 Mmm OP w. l m .V- N H .VM Om 0m om 0mv Nm om mm mm .0m

Tn m i Wm Patrente'd ,May 26, 1942 l i -ffUNITED STAT Y long life-.ofi

V4characterD f Es PA'rffENTr-,orllcs nrnaAunrcrUMe R Mororty. .lames Robinson, fDetroit,-,"Mich., assigner: 'to

Y Application June128, 1939, Serial No.v^281,645

` s claims. (01.103-162) A to design them with a substantial amount of unbalance sufficient to allow for the largest toler- This'gfinvention relates to power 'transmissions and more vparticularly to those of the type comprising two'or more uidjpressure energy translatingdevicea'onefuof whichmay functionas a pumpa'ridanotheras 'a fluid motor. In such de' l vices of the' type whichcomprise a revolving cylinder barrel having a pluralityof parallel cylin- -fder boresltherein within which pistons are reciprocat'ed by a -swashpplate device, it is customary `to providea rotary=valving `mechanism which is operatedl bythe rotation of the cylinder barrel itself-for the purposeof :alternately connecting y `eachcy-lirfirler bore withthe inlet and outlet passages' offthe device. [Many machines of this character utilize'aplate type valve formedby a flat surface-'of thebyiinder barrel which runs in It is customary withmachines of this charac-4 ter to so proportion the sizeof the distributing' ports in .theen'diace of the-'cylinder barrel rela- 'tive'ftoft e-piston area andto the areaA of the'L annularV Vurface, oncontact with the valve plate' `ance variation normally encountered without causing the direction of unbalance to change. If the net unbalance isv in a direction holding the barrel in contact and'is very large,v then the unit bearing pressures at the valve plate are apt tobe' excessive. On the other hand, if the machine is designed for a very small net unbalance tending to hold the barrel in contact it occasionally happens, due to manufacturing variations,` that the net unbalance of the hydraulic forces on the barrel becomes revers-ed andfis in a direction tending to lift the barrel off from the valve plate, and in such cases the spring is suflicient' to maintain the vbarrel in contact with the valve plate vat all operating pressures below a certain maximum. When this maximumis exceeded, how-r l -ever, the barrel lifts away from the valve plate,

and since the valve is thereby rendered ineffective, the power drive through the transmission 1 isA completely and suddenly interrupted. This diiculty can be extremely troublesome at times. I

- particularlywhere the. transmission is usedto as ,toolosely approach'hydraulic balance between the iiuid pressure forcesexerted by piston reacf `ticmaon the end `faces of the cylinder` bores and.` .the' ,fluid .pressure separating forces exerted in resilient means is usually provided for urging Ithebarel"into'contact with the valve plateV with Q ya relatively light force at all times.

is lextremelydifficult to predetermine with '.precision lthe exact amount .of hydraulic unbal- Y ance .which will exist in a givenmachine since lsmall variationsin dimensions which are :entirely within normal manufacturing tolerances 4 `produce large changes inthe hydraulic balance when the operating pressures are high. Thus,

y in order to insure that, in Vspite of tolerance variations,V all machines Willhavea positive unbal- A vpopi irser. impossible in practice to provide yanhexact' .lfn'alance between these forces, end sincelit 'is necessaryv tolprovide some meansfor Vholdingthe ba'rrelfin" contactwith the valveA ip late while theimachine'is idle,.a spring orother operate a device, such as av hoist, which has' to overcome agravity load 'and in Whichcomplete dependence upon'the transmission is placed for sustaining thatv load. yIn'such/cases itA occasionally happens that lthe critical rpressure at which the barrel will blow oli is slightly'above the nor-A rmal operating pressure required for lifting theV usual loads and that on rare occa-sionsL due to snagging of hoisting Ylines orsome other momentary lsmall overloadA during hoisting, thecrltical pressure'is exceeded causing Vthe barreltolift and resulting'indropping 'of .the load- Withfconsequent damage thereto.

" It is an object'of the present invention to prl vide a valve plate construction for a fluid pres'- stant. It thereby becomes possible to design theance in the same direction, it would be necessary sure energy translating device of the class de' scribed in which the above problems areavoided by the provision of means for exerting a variable force on the cylinder barrel such that the total forcetending to hold the barrel on the valve plate is not proportional to operating pressure variations -and f preferably substantially `conmachine with a substantial degree of unbalance tending to hold the barrel in Contact at4 low pressures and at the same time' avoid increasing the total force holding it in contact as the oper--v ating pressure increases. At 'the' same time all necessity is avoided of trying to approach true hydraulic lbalanceso closely as to admit of occasional reverses in unbalance in machines hapv pening to come-at -.the

tion of va iluid pressure 'energytranslatingdevice .incorporating a preferred form ofthe present in` tolerance. Y Further objects and advantages. of the` pres'- ent inventionwill 'be apparent from' the follow-- ing description, reference beingv h ad tothe ac- Jcompanying drawing'wherein' afpreferred form .oi thepresent invention is clearlyshown.

. In the drawing:

The single .flgure` isfalongitudinal cross vention.

The embodiment of thelimvlentionV selected for be mounted ion top 'of-.thelspring cup 1I. The

left-hand endof thechamber is in communi-l. cation with'onewotgtlie .valve -plate `ports 43' through-a drilled'passage43.`'1'he: single pasillustration comprises a pump of the same general class asthat illustrated in the patent to Hans Thoma,"No. 1,931,969, and `comprises generally. a main ring-like framemember Ill-havinga mounting flange l2thereonv andprovide'd with bearings I4 on -which `a main shaft II' is journalled;` The shaft-i lisfprovided .with a socket ilange lli-carryinga plurality of ball sock. ets T in which'arejmounted ball-ended connectingrods 22 carryingreciprocating.pistons l24.

Rigidly secured to the `frame member I0 by suitable bolts not shown arctal pair of plates 23A provided with .bearings 2t and with ilud connections 30. Journalled on thebearings 28.is\a

prising .a valve plate 34 with rigidly attached hollow arms 36 providing trunnions for the yoke and connected tothe iluid connection by sealing sleeves 38.

'Ihe valve plate 34 is provided with an arcuate raised sealing surfaceA 4l .against which runs the tlat end face 42 of a cylinder barrel 44 provided cal between the abutment"12"an`d a` spring cup 'I4 rigidly secured to 'the left-hand end of the valve plate 34. A'suitable cap 1 8 maybe mountedon top liithe valveplate 34.? A suitable' cap 13 may sage'lll is suitable for useawithpumps' or motors of the type where thehigh operating .pressure is alwaysatoneport of the machine'and is never.

reversed. For devices vwhere th'e'lhigh pressure side may be at one or thefgother oi the .ports 4 4 ofa shuttle valve operating linthe well-known draining the rightfhand-end of chamber il.'

In' operation, Vassuming that theconduits 34 are yconnected into a power transmission circuit in .--.the usual manner so that the upper conduit 3l swinging yoke generally designatedl as 32-fcom.

with a plurality .of cylinder l.bores 46 therein.

iiuld distributingpo'rts 4I each of which extends through an arc somewhat less than 180 degrees and communicates with the-passages in theholf low anns .36. Formed at the leftfhand end of the 4Formed in the v al've plate 34` are two arcuate. y

is the pressure'su'pply connection while the lower one is the suction connection and that the shaft I6 is connected to a suitable prime moyer and rotated thereby at a constant speed, with the top moving away fromthe observer-the pistons 24 are 'reciprocated in th cylinder bores 46 in the well-known manner with a stroke. depern'lingI upyonr the angulardisplacementof vthe .yoke 32. l With the left-hand endv of thefyoke moved away from the observer each piston 24 will travel to the left during its top-half revolution and y Wi11`be Withdrawnlto'the right during its bottomcylinder 'bores 46 are a plurality ofnuid distrlbdistributingports 43.' A shaft 52 provided with funiversal joints 54 -at rits .opposite',ends co'n-lnectslth'ebarrelj-M torotate-'with the shaft all uting ports 50 opening into the; ilat. face 42 and.

adapted to alternately register'with eachoi'the; v

many position or the yoke' 3215" The parts thus.

fardescribed are in a broadaspectwell known; in the art andj per se form no `part..o'f the present invention'.

The hydraulic-balance of the cylinder vbarrel tioning ofthe radialy width of the nat pressure lsurface relative to the-total area of all of.- the ports il and Ithe total ar'eaof 4all of the pistons 24. With the present invention. these areas are so proportioned as to produce a'netiluid pressure forceon the cylinder barrel 44' tending to urge unbalance is made as small as possible, however.-

andA is, of course', proportional tothe operating Pressure.' l

According'to the invention, means is provided :for additional f orce tending to urge the barrel into contactwith the surface 40 which half revolution, thus withdrawing 'iluid fromthe 'lower port 43 into the cylinder, 43 and discharging it outof them into the lippr'portl.

At zero operating pressure in thev upper port l43 1 the pressure in chambervlgislikewise zeroand the two springs ;'|4"a.ncl4 .balance one another f so that each exerts `anfequal force.' 'I'hewforceof vvspring I3 is transmitted through' the. bearing I5I to the cylinder barrel-44 and is the sole'force urging the barre1 uitpbcontact with the valve -44 is, o! course, determined bysuitable propor- 4the .barrel intocontsctlwiththe surface an. x This portion to increases in fport 43. s

. plate. As the pressurefih the-upper port 4l in-l creases this pressure is` transmitted to the .cham- 'bei-.ss and moves the piston interner-ign; by i an amount proportional to-the'increase in pres- `sure, thus increasing thegtensi'ori on the .spring .14 'and decreasing the tensionv on the spring Il. Accordingly .the force whiclithe4 spring Si exerts on the cylinder barre1"44 is' decreased vin propressure in the upper The force which the hydraulic 'num 1n the cylinders 46 exerts onl thefcylinder barrel. that is, the net hydraulic unbalanceof, the barrel, increases in direct proportion, to the pressure in port 4l so that' accordin81y-the'total force exerted comprises a spring ,the lefthand end of winch abuts the inner' race of aball'bearing Il' the -outer race of' which rests against a shoulder;

formed at the left-hand end oi' a recess il formed inthe barrel 44. The right-hand end of the spring 53 is positioned by a'spring abutment 42 rigidly secured to the end oi a rod 44 mounted in' abore I4 in the valve plate 34.

Also formed in thevalve plate `34 is a cylindri- `on the cylinder barrel ;44 remains .substantially f constant. Obviously the designed proportions o ithe device may be varied' in'such a manner as to provide either-exactly 'constant force onv the. barrel 44 or to provide increasingpressure or vice versa depending upon the balance oi'v design factors such as the 'rate of spring 5l, the area of the 'piston 10, and the net hydraulic unbalance of the barrel 44.

While the form of embodiment of the invention as herein disclosedonstitutes a preferred i .hmber l' 111Whichialisiably.amounted@v f ffpistqn 1n integrsny-rormedfon the; rou` n.11 vThe .A f f! `left-hand endofL the rod-marries rin-adjustable."

. spring abutment '12.' A-sprint is interposed' `form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. In a fluid pressure energy translating device having a plurality of cylinders and pistons reciprocable therein, a rotary valve structure comprising two relatively rotatable members provided lwith fiat, annular, sealing surfaces in running engagement and containing uid distributing ports communicating with said cylinders, one of said members having-an area exposed to iiuid pressure from said'cylinders tending to urge said member'into abutment with force proportional to saidpressure, resilient means also tending to urge said members into abutment, and pressure responsive means including-a spring-biased uid motor acting through said resilient means on said member for varying the force of said resilient means in inverse proportionto said pressure.

2. In a iiuid pressure energy translating device having a plurality of cylinders and pistons reciprocable therein, a rotary valve structure comprising two relatively rotatable members provided with at, annular, sealing surfaces in running engagement and containing Yfluid distributing ports communicating 4with' said cylinders, said members being hydraulically balanced against at least a major portion of the separating force normally existing betweemsaid surfaces, an expansible chamber 'in communication with one of said -ports and having a spring-biased movable member, and means forming a resilient connection between saidmovable member and one of said rotatable members through which said movable member acts on the rotatable member.

3. 'In a fluid pressure energy translating device of the type having a revolving cylinder barrel with a plurality of cylinders therein and pistons reciprocable in the cylinders, a rotary valve strucp ture comprising a stationary valve having a iiat annular surface with fluid distributing ports in inverse proportion to said pressure. L

4. In a fluid pressure energy translating device of thetype having a revolving cylinder barrel with a plurality-of cylinders therein and pistons reciprocable in the cylinders, a rotary valve structure comprising a stationary valve havinga fiat annular surface with iuid distributing ports therein, means forming a at annular surface on the cylinder barrel adapted to abut the valve plate surfaceand provided with iluid dis-- tributing ports therein, said barrel being hydraulically balanced against at least a major portion of the separating force normally existing between said surfaces, an expansible chamber-in 'communication with one of said ports and having a spring-biased movable member, and means forming a resilient connection between said'mov-l able member and the cylinder barrel -through which said movable member acts on the rotatable member.

5. In -a fluid pressure energy translating device having a plurality oi cylinders and pistons reciprocable therein, a rotary valve structure comprising two relatively rotatable members provided with flat, annular, sealing surfaces in running engagement and -containing uid distributing ports communicating with said cylinders, saidv members being-subject to a net hydraulic force tending to hold the members against separation, resilient means for applying additional force holding the members against separation, and means including a spring-biased fluid motor acting through said resilient means on said member, for decreasing the force of the resilient meanswith increases `in operating pressure of. the device. y

' 6. In a uid pressure energy translating device of the type having a revolving cylinder barrel'with a plurality of cylinders therein and pistons reciprocable in the cylinders, a rotary valve structure comprising a stationary valve having a flat annular surface with fluid distributing ports therein, means forming a flat annular surface on the cylinder .barrel adapted to abut the valve f plate surface and provided with uid distributing ports therein, said barrel being subject to a net hydraulic force tending to hold the barrel i against the valve plate, resilient means for applying additional Iforce in the same direction,

and means including a spring-biased uid motor actingthrough said resilient means on said member for decreasing the force of the resilient means with increases in operating pressure of the de vice,"

JAMES ROBINSON.

ber for varyingthe force of said resilient means 

